From 954749368bc34b7171791be6b1d30aecadb50e11 Mon Sep 17 00:00:00 2001 From: dillon Date: Sat, 28 Dec 2002 23:39:47 +0000 Subject: Add 'swapctl' - as a hardlink to swapon/swapoff, and augment swapon with swapctl functionality. The idea is to create a swapctl command that is fairly close to the OpenBSD and NetBSD version. FreeBSD does not implement swap priority (and it would be a mistake if we did) so we didn't bother with that part of it. Submitted by: Eirik Nygaard Augmented by: dillon (extensively) Reviewed by: David Schultz --- sbin/swapon/swapon.8 | 101 +++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 78 insertions(+), 23 deletions(-) (limited to 'sbin/swapon/swapon.8') diff --git a/sbin/swapon/swapon.8 b/sbin/swapon/swapon.8 index edda998..cb6cd00 100644 --- a/sbin/swapon/swapon.8 +++ b/sbin/swapon/swapon.8 @@ -43,39 +43,94 @@ .Fl a .Nm swap[on|off] .Ar special_file ... +.Nm swapctl +.Fl lshk +.Nm swapctl +.Fl AU +.Nm swapctl +.Fl a +.Ar special_file ... +.Nm swapctl +.Fl d +.Ar special_file ... .Sh DESCRIPTION The +.Nm swap[on,off,ctl] +utilties are used to control swap devices in the system. At boot time all +swap entries in +.Pa /etc/fstab +are added automatically when the system goes multi-user. +Swap devices are interleaved and kernels are typically configured +to handle a maximum of 4 swap devices. There is no priority mechanism. +.Pp +The .Nm swapon -utility is used to specify additional devices on which paging and swapping -are to take place. -The system begins by swapping and paging on only a single device -so that only one disk is required at bootstrap time. -Calls to -.Nm swapon -normally occur in the system multi-user initialization file -.Pa /etc/rc -making all swap devices available, so that the paging and swapping -activity is interleaved across several devices. +utility adds the specified swap devices to the system. If the +.Fl a +option is used, all swap devices in +.Pa /etc/fstab +will be added, unless their ``noauto'' option is also set. .Pp The .Nm swapoff -utility disables paging and swapping on a device. -Calls to +utility removes the specified swap devices from the system. If the +.Fl a +option is used, all swap devices in +.Pa /etc/fstab +will be removed, unless their ``noauto'' option is also set. +Note that .Nm swapoff -succeed only if disabling the device would leave enough -remaining virtual memory to accomodate all running programs. +will fail and refuse to remove a swap device if there is insufficient +VM (memory + remaining swap devices) to run the system. +.Nm Swapoff +must move swapped pages out of the device being removed which could +lead to high system loads for a period of time, depending on how +much data has been swapped out to that device. .Pp -Normally, the first form is used: -.Bl -tag -width indent -.It Fl a -All devices marked as ``sw'' -swap devices in +The +.Nm swapctl +utility exists primarily for those familiar with other BSDs and may be +used to add, remove, or list swap. Note that the +.Fl a +option is used diferently in +.Nm swapctl +and indicates that a specific list of devices should be added. +The +.Fl d +option indicates that a specific list should be removed. The +.Fl A +and +.Fl D +options to +.Nm swapctl +operate on all swap entries in .Pa /etc/fstab -are added to or removed from the pool of available swap -unless their ``noauto'' option is also set. -.El +which do not have their ``noauto'' option set. .Pp -The second form is used to configure or disable individual devices. +Swap information can be generated using the +.Nm swapinfo +program, +.Nm pstat +.Fl s , +or +.Nm swapctl +.Fl lshk . +The +.Nm swapctl +utility has the following options for listing swap: +.Bl -tag -width indent +.It Fl l +List the devices making up system swap. +.It Fl s +Print a summary line for system swap. +.It Fl h +Output values in megabytes. +.It Fl k +Output values in kilobytes. +.Pp +The BLOCKSIZE environment variable is used if not specifically +overridden. 512 byte blocks are used by default. +.El .Sh SEE ALSO .Xr swapon 2 , .Xr fstab 5 , -- cgit v1.1